Method and system for encoding a signal for wireless communications

ABSTRACT

Method and system encodes a signal according to a code rate that includes a ratio of uncoded bits to coded bits. An outer Reed-Solomon encoder encodes the signal into codewords. An interleaver converts the codewords into bits of frames for wireless transmission. An inner encoder executes a convolutional code to generate an encoded signal. The encoded signal is transmitted over a plurality of subcarriers associated with a wide bandwidth channel. The convolutional code is punctured and code states are added by the inner encoder to improve the code rate.

This patent application claims priority under 35 USC § 119 to thefollowing co-pending patent applications: U.S. Provisional PatentApplication Ser. No. 60/544,605, filed Feb. 13, 2004; U.S. ProvisionalPatent Application Ser. No. of 60/545,854, filed Feb. 19, 2004; U.S.Provisional Application Ser. No. 60/568,914, filed May 7, 2004; and U.S.Patent Provisional Application Ser. No. 60/575,909, filed Jun. 1, 2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to wireless communication systems andmore particularly to a transmitter transmitting at improved data rateswith such wireless communication systems and methods of encoding signalsto achieve the data rate.

2. Description of the Related Art

Wireless and wire lined communications may occur between wireless orwire lined communication devices according to various standards orprotocols. Communication systems and networks may include national orinternational cellular telephone systems, the Internet, point-to-pointor in-home wireless networks and the like. A communication system isconstructed, and may operate in accordance with the standard. Forexample, wireless communication systems may operate in accordance withone or more standards including, but not limited to, IEEE 802.11,Bluetooth, advanced mobile phone services (AMPS), digital AMPS, globalsystem for mobile communications (GSM), code division multiple access(CDMA), local multi-point distribution systems (LMDS),multi-channel-multi-point distribution systems (MMDS), and the like.

Wireless local area networks (WLAN) that may use IEEE 802.11, 802.11a,802,11b, or 802.11g that employ single input,single output (SISO)wireless communications. Other types of communications include multipleinput, single output (MISO), single input, multiple output (SIMO), andmultiple input, multiple output (MIMO). With the various types ofwireless communications, it may be desirable to use the various types ofwireless communications to enhance data throughput within a WLAN.

For example, improved data rates may be achieved with MIMOcommunications in comparison to SISO communications. Most WLAN, however,include legacy wireless communication devices that are devices compliantwith an older version of a wireless communication standard. Thus, atransmitter capable of MIMO wireless communications also may be backwardcompatible with legacy devices to function in a majority of existingWLANs. One factor for backward compatibility is that transmitters,receivers, and the like assume all signals with a system are valid.

BRIEF SUMMARY OF THE INVENTION

A system for generating a signal for wireless communication isdisclosed. The system includes an outer encoder to execute outerencoding having a first rate on a signal to generate at least onecodeword. The system also includes an interleaver to interleave the atleast one codeword into a plurality of frames. The system also includesan inner encoder to execute convolutional encoding having a second rateon the plurality of frames to generate an encoded signal. The first rateand the second rate produce an overall coding rate corresponding with awide bandwidth channel.

A method for generating a signal for wireless communication also isdisclosed. The method includes executing an outer encoding process on asignal. The outer encoding process has a first rate. The method alsoincludes generating at least one codeword from the outer encoding. Themethod also includes interleaving the at least one codeword into aplurality of frames. The method also includes convolutional encoding theplurality of frames. The convolutional encoding has a second rate togenerate an encoded signal according to an overall coding rate producedby the first rate and the second rate. The overall coding ratecorresponds to a wide bandwidth channel.

A method for encoding a signal for wireless transmission also isdisclosed. The method includes generating a codeword from a signal usinga Reed-Solomon encoding process. The Reed-Solomon encoding process has afirst rate. The method also includes generating an encoded signal fromsaid codeword using a convolutional encoding process having a secondrate. The first rate and the second rate produce an overall coding rateapplication for a wide bandwidth transmission.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a wireless communication system in accordance withthe present invention;

FIG. 2 illustrates a wireless communication device in accordance withthe present invention;

FIG. 3 illustrates an encoding system in accordance with the presentinvention;

FIG. 4 illustrates a transmitter in accordance with the presentinvention;

FIG. 5 illustrates a flowchart for encoding data in accordance with thepresent invention;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made to the following detailed description of thepreferred embodiments of the present invention. Examples of preferredembodiments may be illustrated by the accompanying drawings.

FIG. 1 depicts a communication system 10 according to the presentinvention. Communication system 10 may be a wireless communicationsystem having networks supported by various wireless communicationstandards or protocols. Communication system 10 includes stations 12, 14and 16. Stations 12, 14 and 16 may provide access for wireless devicesand components to communication system 10. Communication system 10 mayprovide services and content to the devices and components via stations12, 14 and 16.

Communication system 10 also may include wide area networks (WANs),local area networks (LANs), wireless local area networks (WLANs), ad-hocnetworks, virtual networks, and the like to facilitate the exchange ofinformation or data. For example, network 20 may be coupled to stations12, 14 and 16 and support communications with communication system 10.

Communication system 10 may forward data or information in the form ofsignals, either analog or digital. Wireless devices within theindividual base stations may register with the base stations and receiveservices or communications within communication system 10. The wirelessdevices may exchange data or information via an allocated channel.Network 20 may set up LANs to support the channel. To support thewireless communication, communication system 10 and its applicablenetworks may use a standard of protocol for wireless communications. Forexample, the IEEE 802.11 specification may be used. The IEEE 802.11specification has evolved from IEEE 802.11 to IEEE 802.11b to IEEE802.11a and to IEEE 802.11g. Wireless communication devices that arecompliant with IEEE 802.11b (standard 11b) may exist in the samewireless local area network as IEEE 802.11g (standard 11g) compliantwireless communication devices. Further, IEEE 802.11a (standard 11a)compliant wireless communication devices may reside in the WLAN asstandard 11g compliant wireless communication devices.

These different standards may operate within different frequency ranges,such as 5 to 6 gigahertz (GHz) or 2.4 GHz. For example, standard 11a mayoperate within the higher frequency range. One feature of standard 11ais that portions of the spectrum from between 5 to 6 GHz may beallocated to a channel. The channel may be 20 megahertz (MHz) widewithin the frequency band. Standard 11a also may use orthogonalfrequency division multiplexing (OFDM). OFDM may be implemented oversub-carriers that represent lines, or values, within the frequencydomain of the 20 MHz channels. A wireless signal may be transmitted overmany different sub-carriers within the channel. The sub-carriers areorthogonal to each other so that information may be extracted off eachsub-carrier about the signal without appreciable interference.

Legacy devices may exist within communication system 10. Legacy devicesare those devices compliant with earlier versions of the wirelessstandard, but reside in the same WLAN as devices compliant with acurrent or later version of the standard. A mechanism may be employed toensure that legacy devices know when the newer version devices areutilized in a wireless channel to avoid interference or collisions.

Thus, newer devices or components within communication system 10 may usecurrent standards that have backward compatibility with alreadyinstalled equipment. The devices and components may be adaptable tolegacy standards and current standards when transmitting informationwithin communication system 10. Legacy devices or components may be keptoff the air or off the network so as to not interfere or collide withinformation or data that they are not familiar with. For example, if alegacy device receives a signal or information supported by standard11n, then the device should forward the information or signal to theappropriate destination without modifying or terminating the signal orits data. Further, a received signal may not react to the legacy deviceas if the legacy device is a device compatible with a new or currentstandard.

Communication system 10 may operate according to the IEEE 802.11n(standard 11n) protocol for wireless communications. Alternatively,communication system 10 may operate under a variety of standards orprotocols, such as standard 11a, standard 11g and standard 11n and mayinclude legacy devices or components. For example, certain componentsmay comply with standard 11a while newer components may comply withstandard 11n. Standard 11n may occupy the 5 to 6 GHz band, or,alternatively, standard 11n may occupy the 2.4 GHz band. Standard 11nmay be considered an extension of standard 11a. Standard 11n devices andcomponents may operate with a bandwidth of 100 MHz. The devices andcomponents within communication system 10 may know the physical layerrate for standard 11n devices and components may be greater than thoseof previous standards.

Bandwidth for wireless channels under standard 11n may be 20 MHz or 40MHz. Thus, standard 11n may implement wider bands than previousstandards, such as standard 11a. For example, standard 11n may put two20 MHz bands together as a 40 MHz band and may send twice as much dataas previous standards. Moreover, information or data may be filled in agap between the two 20 MHz bands. The gap results due to falloff betweenthe two bands. By filling in the gap, data or information may be sentaccording to standard 11n at a rate twice as much as previous standards,if not more.

Communication system 10 also may include a multiple input, multipleoutput (MIMO) structure. MIMO structures may be implemented incommunication system 10 to improve the robustness of wirelesscommunications. To better improve robustness, communication system 10also may set the number of data streams to be less than the number oftransmitters of a wireless device.

Communication system 10 may resolve the issue of signals generated bylegacy devices or components and having the signals operate within aMIMO system using multiple antennas. For example, communication system10 may determine how the standard 11a signals will work within the widerbandwidth of the channels for standard 11n. Communication system 10 mayincrease the probability of reception of signals transmitting largeamounts of data under current standards or protocols. Further, it may bepresumed that all the devices and components within communication system10 may receive all transmitted signals, no matter what format, protocolor standard is used.

FIG. 2 depicts a wireless communication device 200 according to thepresent invention. Wireless device 200 includes host device 18 and anassociated radio 60. For cellular telephone hosts, radio 60 may be abuilt-in component. For personal digital assistants hosts, laptop hosts,personal computer hosts and the like, radio 60 may be built-in or anexternally coupled component.

Host device 18 may include processing module 50, memory 52, radiointerface 54, input interface 58 and output interface 56. Processingmodule 50 and memory 52 may execute instructions that are performed byhost device 18. For example, for a cellular telephone host device,processing module 50 may perform the corresponding communicationfunctions in accordance with a particular cellular telephone standard,such as standard 11n.

Radio interface 54 may allow data to be received from and sent to radio60. For data received from radio 60, such as inbound data, radiointerface 54 provides the data to processing module 50 for furtherprocessing or routing to the output interface 56. Output interface 56may provide connectivity to an output display device such as a display,monitor, speakers and the like, such that the received data may bedisplayed. Radio interface 54 also may provide data from the processingmodule 50 to radio 60. Processing module 50 may receive the outbounddata from an input device such as a keyboard, keypad, microphone an thelike, via input interface 58 or may generate the data itself. For datareceived via input interface 58, processing module 50 may perform acorresponding host function on the data or route it to radio 60 via theradio interface 54.

Radio 60 may include a host interface 62, a baseband processing module64, memory 66, a plurality of radio frequency (RF) transmitters 68-72, atransmit/receive (T/R) module 74, a plurality of antennas 82-86, aplurality of RF receivers 76-80, and a local oscillation module 100.Baseband processing module 64, in combination with operationalinstructions stored in memory 66, may execute digital receiver functionsand digital transmitter functions, respectively. Baseband processingmodules 64 may be implemented using one or more processing devices.Memory 66 may be a single memory device or a plurality of memorydevices. When processing module 64 implements one or more of itsfunctions via a state machine, analog circuitry, digital circuitry, orlogic circuitry, memory 66 storing the corresponding operationalinstructions is embedded with the circuitry comprising the statemachine, analog circuitry, digital circuitry, or logic circuitry.

The radio 60 may receive outbound data 88 from host device 18 via thehost interface 62. Baseband processing module 64 receives outbound data88 and, based on a mode selection signal 102, produces one or moreoutbound symbol streams 90. Mode selection signal 102 may indicate aparticular mode.

Baseband processing module 64, based on mode selection signal 102, mayproduce one or more outbound symbol streams 90 from output data 88. Forexample, if mode selection signal 102 indicates that a single transmitantenna is being utilized for the particular mode that has beenselected, baseband processing module 64 may produce a single outboundsymbol stream 90. Alternatively, if mode selection signal 102 indicates2, 3 or 4 antennas, baseband processing module 64 may produce 2, 3 or 4outbound symbol streams 90 corresponding to the number of antennas fromoutput data 88.

Depending on the number of outbound streams 90 produced by basebandmodule 64, a corresponding number of the RF transmitters 68-72 may beenabled to convert outbound symbol streams 90 into outbound RF signals92. Transmit/receive (T/R) module 74 may receive outbound RF signals 92and provides each outbound RF signal to a corresponding antenna 82-86.

When radio 60 is in a receive mode, T/R module 74 may receive one ormore inbound RF signals via antennas 82-86. T/R module 74 providesinbound RF signals 94 to one or more RF receivers 76-80. RF receivers76-80 may convert inbound RF signals 94 into a corresponding number ofinbound symbol streams 96. The number of inbound symbol streams 96 maycorrespond to the particular mode in which the data was received.Baseband processing module 60 may receive inbound symbol streams 90 andconverts them into inbound data 98, which are provided to the hostdevice 18 via the host interface 62.

FIG. 3 depicts an encoding system 300 for use with wirelesscommunications according to the present invention. Encoding system 300may be coupled to a transceiver to code signals for transmission withina wireless network or system. Alternatively, encoding system 300 may becoupled to other devices or components for wireless communications.Further, encoding system 300 may be within the transceiver. Encodingsystem 300 also may operate or encode according to an applicablewireless communication standard or protocol. For example, encodingsystem 300 may operate according to standard 11n, so that encodedsignals are formatted to take advantage of the improvements of standard11n over legacy standards.

Encoding system 300 may include outer encoder 302, interleaver 304 andinner encoder 306. Encoding system 300 receives data or information assignal 310 at outer encoder 302. Inner encoder 306 outputs coded signal312. A code rate may be determined by comparing signal 310 with codedsignal 312. The code rate also may be referred to as an overall codingrate. For example, a code rate may be the ratio of uncoded bits insignal 310 to the coded bits in coded signal 312. Encoding system 300may improve the code rate over legacy systems so as to comply withstandard 11n. For example, coding system 300 may have a code rate of 0.8at 100 megabits/second for a channel having a 20 MHz bandwidth.Constraints applied by standard 11n may warrant a high code rate toincrease the ratio of uncoded bits to coded bits over legacy standards.Thus, outer encoder 302, interleaver 304 and inner encoder 306 mayoperate according to the constraints and a target code rate of 0.8.

Encoding system 300 may code bits to improve performance over a systemof uncoded bits. A tradeoff, however, may exist between performance andcomplexity of encoding system 300. Thus, if encoding system 300 becomestoo complex, any benefit from improved performance may be offset byhigher costs in constructing and implementing encoding system 300.

Outer encoder 302 may include a Reed-Solomon (R-S) encoder. An R-Sencoder may be applicable for coding longer frames. When encoding,encoding system 300 may forward longer frames with an increasedprobability of being received correctly. Outer encoder 302 may implementthe R-S encoder even if the applicable wireless standard uses shortframes. Further, outer encoder 302 may be separable from anyconvolutional coding, such as that done by inner encoder 306. Outerencoder 302 may receive data or information as bits and then codes thebits into bytes for interleaver 304. For example, outer encoder 302 maygenerate 2-5 code words comprised of bytes. For example, a code word 320may include about 255 bytes with about 239 information bytes. Thus,codeword 320 also may include about 16 redundant bytes.

Interleaver 304 receives code word 320 to perform interleaving on thebytes in code word 320, and to generate bits 330. Interleaver 304 may bea byte interleaver. Interleaver 304 may reduce an error rate of encodingsystem 300 because it may resolve bit errors before the errors arrive atinner encoder 306. Bit errors from outer encoder 302 may be randomlygenerated, but also may occur in bursts. Interleaver 304 may operateaccording to a specified rate or operator.

Inner encoder 306 receives bits 330 and performs convolutional coding togenerate coded signal 312. Inner encoder 306 may be a convolutionalencoder that in conjunction with outer encoder 302 establishes thedesired code rate. For example, inner encoder 306 and outer encoder 302may work together to develop a code rate of about 0.8. Inner encoder 306and outer encoder 302, however, may be separable from each other. Thus,outer encoder 302 and its encoding schemes may be removed or changedwithin encoding system 300 without impacting inner encoder 306, or itsconvolution code. Thus, modularity between the encoding schemes mayexist to improve performance without increased complexity to existingsystems, or the need of new code or devices for encoding system 300.

Further, the convolutional code of inner encoder 306 may be punctured at7/8s on a binary convolutional code. The coding rate of inner encoder306 may generate a code rate of 0.8 for encoding system 300, whencombined with the code rate of outer encoder 302. Referring back to theR-S encoder, examples of the R-S code may have a rate that is multipliedby the code rate of a 7/8s convolutional code to achieve a code rate0.8. Further, inner encoder 306 may be a convolutional encoder operablewith legacy standards, such as standard 11a.

Coded signal 312 may include frame 332. Frame 332 may be one of manyframes within coded signal 332. Frame 332 includes preamble, or header,field 334 and data field 336. Preamble field 334 may be referred to as apreamble. Preamble 334 may include data or information regarding frame332 or coded signal 312. The information may include, but is not limitedto, length of frame 332. Alternatively, preamble 334 may includeinformation regarding code words from outer encoder 302 or informationabout coded signal 312. Preamble 334, however, is not so large as tomake frame 332 unreadable or unusable. Preamble 334 also may includeshort and long training fields.

With regard to inner encoder 306, it may be the same convolutionalencoder as used in conjunction with standard 11a. Puncturing of theconvolutional code according to standard 11a may also be ⅔ and ¾.Options may be added for these codes, such as a 256 state code or newpuncturings for rates of 4/5, 5/6 and 7/8, as discussed above. Thus,inner encoder 306 may be an encoder having the above rates. Moreover,the options listed above may be combined, if desired.

Interleaver 304 may be in different states for operation within encodingsystem 300. One state may be an “off” state, wherein encoding system 300acts as if no interleaver 304 is present. Another state may be as aninterleaver having sufficient depth to randomize the demodulated bitsover R-S code words, such as code word 320.

Outer encoder 302 may operate or generate code words having multiplelengths. As noted above, a code word 320 may have a length of about 255,or n, with an information sequence length of about 239 bits, or k. Thus,a correction of up to 8 byte errors may be allowed per code word fromouter encoder 302.

For an effective code rate of about 0.8, encoding system 300 may executea coding process that achieves a gain of about 4 dB, or above over theconvolutional coding scheme alone. Further, additional components may beincluded in encoding system 300. The coding processes of outer encoder302 and inner encoder 306 may differ from each other.

FIG. 4 depicts a block diagram of a transmitter 400 according to thepresent invention. Transmitter 400 includes scrambler 472, channelencoder 474, interleaver 476, demultiplexer 470, a plurality of symbolmappers 480, 482 and 484, a plurality of inverse fast Fourier transform(IFFT) modules 486, 488 and 490 and encoder 492. Transmitter 400 alsomay include a mode manager module 475 that receives a mode selectionsignal and produces settings for transmitter 400.

Scrambler 472 may add a pseudo-random sequence to outbound data bits 488so that the applicable data or information may appear random. Apseudo-random sequence may be generated from a feedback shift registerhaving a generator polynomial to produce scrambled data. Channel encoder474 may receive the scrambled data and generate a new sequence of bitshaving redundancy. The new sequence may enable improved detection at areceiver. Channel encoder 474 may operate in one of a plurality ofmodes. These modes may correspond to standards or protocols for wirelesscommunications. For example, modes may be assigned to standard 11a,standard 11g, or standard 11n. Backward compatibility with standard 11aand standard 11g may be achieved. Further, channel encoder 474 may be aconvolutional encoder with 64 states and a rate of 1/2. The output ofchannel encoder 474, as a convolutional encoder, may be punctured torates of 1/2, 2/3 and 3/4. For backward compatibility with standard 11band the CCK modes of standard 11g, channel encoder 474 may have the formof a CCK code as defined in standard 11b.

For improved data rates, such as those desired by standard 11n, channelencoder 474 may use the same convolutional encoding, as described above.Alternatively, channel encoder 474 may use a more powerful code,including a convolutional code with more states, a parallelconcatenated, or turbo, code or a low-density parity check block code.In addition, any one of these codes may be combined with an R-S codewith an outer encoder being a Reed-Solomon encoder. The choice ofapplicable code may be determined according to backward compatibilityand low-latency requirements.

Interleaver 476 may receive the encoded data and spread it over multiplesymbols and transmit screens. This distribution may allow improveddetection and error correction capabilities at a receiver. Interleaver476 may follow standard 11a or standard 11g in backward compatiblemodes. For increased performance modes, such as those associated withstandard 11n, interleaver 476 may interleave data over multiple transmitstreams. Thus, these modes may be applicable to MIMO configurations.Demultiplexer 470 may convert the serial interleave stream frominterleaver 476 into parallel streams for transmission.

Symbol mappers 480, 482, and 484 may receive a corresponding one of theparallel paths of data from demultiplexer 470. Transmitter 400 mayinclude any number of symbol mappers and is not limited to the aspectsshown by FIG. 4. Further, the number of parallel data streams may varyaccording to the requirements of transmitter 400. For example, thenumber of data streams may correspond to a number of antennas used fortransmitting. Further, the number of symbol mappers may correspond tothe number of antennas.

Symbol mappers 480, 482 and 484 may map the bit streams, or datastreams, to quadrature amplitude modulated (QAM) symbols. The mapsymbols generated by symbol mappers 480, 482 and 484 may be provided toIFFT modules 486, 488 and 490. IFFT modules 486, 488 and 490 may bereferred to as cyclic prefix addition modules. The number of IFFTmodules may correspond to the number of symbol mappers and data streams.IFFT modules 486, 488 and 490 may perform frequency domain to timedomain conversions and may add a prefix that allows removal ofinter-symbol interference at a receiver. The length of the IFFT and anyapplicable cyclic prefix may be defined. For example, a 64 point IFFTmay be used for 20 MHz channels and 128 point IFFT may be used for 40MHz channels, such as those used according to standard 11n.

Encoder 492 may receive the parallel paths of time domain symbols andconvert them into output symbols. Encoder 492 also may be referred to asa space/time encoder. The number of input paths to encoder 492 may equalthe number of output paths. Alternatively, the number of output pathsmay equal the number of input paths plus 1. For each of the paths,encoder 492 multiplies the input symbols with an encoding matrix havinga form shown in Equation 01 below. $\begin{matrix}\begin{bmatrix}C_{1} & C_{2} & C_{3} & \ldots & C_{{2M} - 1} \\{- C_{2}^{*}} & C_{1}^{*} & C_{4} & \ldots & C_{2M}\end{bmatrix} & (01)\end{matrix}$

The rows of the encoding matrix may correspond to the number of inputpaths and the columns may correspond to the number of output paths.Thus, outbound data bits 488 may be encoded and prepared fortransmission by transmitter 400, and converted to multiple outputstreams. Thus, transmitter 400 may support multiple output structuresand operations.

FIG. 5 depicts a flowchart for encoding data for wireless communicationsaccording to the present invention. The steps shown in FIG. 5 may beused for converting outbound data into one or more outbound data streamsfor multiple output transmission. Step 502 executes by receiving databits for transmission. The bits may be generated or created fortransmission in a wireless network or system according to a standard orprotocol. For example, standard 11n may be applicable to the system ornetwork that exchanges the data bits. Alternatively, the applicablesystem or network may have standard 11a and standard 11n devices orcomponents. Thus, the received bits may be received by legacy devices.

Step 504 executes by encoding the bits according to an outer encoder,such as outer encoder 302 in FIG. 3. The outer encoder may encode thebits according to the specified encoding process, such as Reed-Solomonencoding. For example, the outer encoder may be an R-S encoder. The R-Sencoder may be effective in coding longer frames. Step 504 performs theouter encoding of the received bits. Step 506 executes by generatingcode words from the outer encoder. The code words may be bytes. Asdiscussed above, the code words may include about 255 bytes.

Step 508 executes by interleaving the code words from bytes into bits.Thus, the received code words from the outer encoder may be interleavedinto bits for use of multiple data streams. An interleaver, such asinterleaver 304, may be implemented. Alternatively, step 508 may beskipped if no outer encoding is performed on the received bits. Forexample, the received bits may be meant for a network or system havingonly legacy devices, such as those compatible with standard 11a. Thereceived bits, in this example, may not undergo outer encoding toimprove performance and to increase throughput. Thus, step 508 may beskipped.

Step 510 executes by encoding the interleaved bits according to an innerencoder, such as inner encoder 306. For example, the inner encoder maybe a convolutional encoder. The convolutional encoder may encode thebits using convolutional coding techniques. The convolutional encodermay encode the bits to produce a sequence of coded output bits. Theconvolutional encoder may process multiple symbols at a time. The innerencoder also may be specified such that if the encoder receives a numberof input bit streams, then an input vector length may be determined. Anoutput vector length also may be determined according to the number ofoutput bit streams. Thus, the received bits may be coded according tothe convolutional encoder, or the inner encoder. The inner encoder maycode to a specified rate, such as ½. Alternatively, the inner encodermay code to other rates, such as ¾, ⅘ and ⅞.

Step 512 executes by puncturing the coded bits. Step 512 mayperiodically remove bits from the encoded bit streams received from theinner encoder. Thus, the code rate may be increased. A puncture patternmay be specified by a puncture vector parameter. A puncture vector maybe a binary column vector that indicates a bit in a correspondingposition of an input vector is sent to the output vector, or is removed.Thus, bits in various positions may be transmitted while bits and otherpositions may be removed. For example, for every 7 bits of input, thepunctured code generates 8 bits of output. Thus, the puncture rate maybe 7/8.

The code rate may be determined by the puncture convolutional code rateand the code rate of the outer encoder. For example, the Reed-Solomoncode rate may be multiplied by the punctured convolutional code rate toachieve a higher code rate. As discussed above, a code rate may be equalto about 0.8.

Thus, various embodiments of an encoder system and applicable methodsfor use in wireless communication systems is disclosed. As one ofaverage skill in the art will appreciate, other embodiments andvariations thereof may be derived from the teaching of the presentinvention without deviating from the scope of the claims and theirequivalents.

1. A method for generating a signal, the method comprising: encoding asignal using a Reed-Solomon code to generate at least one codeword;converting said at least one codeword into a plurality of frames;encoding said plurality of frames using a convolutional code by addingcode states and puncturing said convolutional code to generate anencoded signal, wherein said convolutional code corresponds to a legacywireless standard.
 2. The method of claim 1, further comprisingtransmitting said encoded signal over a plurality of subcarriers,wherein said plurality of subcarriers corresponds to a current wirelessstandard.
 3. The method of claim 1, further comprising determining anoverall code rate using a first rate of said Reed-Solomon code and asecond rate of said convolutional code.
 4. The method of claim 3,wherein said determining comprises determining said overall rateincludes determining a ratio of above or approximately 0.8 for uncodedbits of said signal to coded bits of said encoded signal.
 5. The methodof claim 1, wherein said encoding said plurality of frames comprisesadding code states having approximately 64 states.
 6. The method ofclaim 1, wherein said encoding said plurality of frames comprisespuncturing said convolutional code at about a 7/8 puncture rate.
 7. Themethod of claim 1, wherein said converting comprises interleaving saidat least one codeword into said plurality of frames.
 8. A device togenerate a signal for wireless communication, the device configured to:encode a signal using a Reed-Solomon code to generate at least onecodeword; convert said at least one codeword into a plurality of frames;encode said plurality of frames using a convolutional code by addingcode states and puncturing said convolutional code to generate anencoded signal, wherein said convolutional code corresponds to a legacywireless standard.
 9. The device of claim 8, wherein the device isconfigured to determine an overall code rate using a first rate of saidReed-Solomon code and a second rate of said convolutional code.
 10. Thedevice of claim 8, wherein said code states include approximately 64code states.
 11. The device of claim 8, wherein said convolutional codeis punctured at approximately a 7/8 puncture rate.
 12. A method forencoding a signal for wireless communication, the method comprising:encoding a signal using a Reed-Solomon encoder to generate at least onecodeword at a first rate; and encoding said codeword to generate anencoded signal using a legacy convolutional code having a second rate byadding code states and puncturing said legacy convolutional code. 13.The method of claim 12, further comprising transmitting said encodedsignal over a channel associated with a current wireless standard. 14.The method of claim 13, wherein said encoding said codeword comprisesusing said legacy convolutional code associated with a legacy wirelessstandard.
 15. The method of claim 12, further comprising determining anoverall code rate from said first rate and said second rate.
 16. Adevice to encode a signal for wireless communication, the deviceconfigured to encode a signal using a Reed-Solomon encoder to generateat least one codeword at a first rate; and encode said codeword togenerate an encoded signal using a legacy convolutional code having asecond rate by adding code states and puncturing said legacyconvolutional code.
 17. A system for generating a signal, the systemcomprising: first encoding means for encoding a signal using aReed-Solomon code to generate at least one codeword; converting meansfor converting said at least one codeword into a plurality of frames;second encoding means for encoding said plurality of frames using aconvolutional code by adding code states and puncturing saidconvolutional code to generate an encoded signal, wherein saidconvolutional code corresponds to a legacy wireless standard.
 18. Thesystem of claim 17, further comprising transmitting means fortransmitting said encoded signal.
 19. The system of claim 17, furthercomprising interleaving means for interleaving said at least onecodeword into said plurality of frames.
 20. A system for encoding asignal for wireless communication, the system comprising: first encodingmeans for encoding a signal using a Reed-Solomon encoder to generate atleast one codeword at a first rate; and second encoding means forencoding said codeword to generate an encoded signal using a legacyconvolutional code having a second rate by adding code states andpuncturing said legacy convolutional code.
 21. The system of claim 19,further comprising interleaving means for interleaving said at least onecodeword into said plurality of frames.